Telephone system.



H. W. ULRICH.

TELEPHONE SYSTEM. -APPUCATION FIL'ED MAR. 30. 1918.

Patented Nov. 12, 1918.

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HORACE W. ULRICH, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Patented Nov. 12, 1918.

Application filed March 30, 1918. Serial No. 225,685.

To all whom it may concern:

Be it known that I, HORACE W. ULRICH,

.a citizen of the United States, residing at East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to such systems in which are employed line or trunk circuits terminating at a central ofiice and provided with line signals.

In such systems at present in use where trunk circuits are employed between central offices and private branch exchanges, if the central office link circuit, at the termination of a conversation, is disconnected from the trunk circuit before the private branch exchange link circuit is disconnected therefrom, the line signaling device associated with the trunk circuit at the central ofiice operates and furnishes a false signal to the operator. In the case of a line circuit, if the link circuit is disconnected from the line before the receiver is restored to its switchhook, the line signaling device then operates and furnishes a false signal. It is the object of this invention to provide a. system in which this false operation of the line signaling device is prevented.

In accordance with this invention a line (or trunk) circuit is provided with a relay which operates upon the connection of a central ofiice link circuit therewith and remains operated upon the disconnection of the link circuit while the line (or trunk) is closed, to prevent the false operation of the line signal, and which is then released upon the subsequent connection of a link ircuit with the line (or trunk) to restore the associated line (or trunk) apparatus to normal condition.

For a more complete understanding of this invention reference should be had to the following description considered 1n connection with the accompanying drawmgs, wherein Figure 1 shows a line circuit lllIlS- trating one embodiment of the invention, and Fig. 2 illustrates another embodiment thereof.

In Fig. 1 of the drawings there is shown a telephone line A terminating at a central ofiice, at which is located a cord circuit B for extending the telephone line. The telephone line A is provided With the usual line relay and cutoff relay 6, and is also provlded wlth two relays 7 and 8 which cooperate with the line and cutoff relays to prevent the false operation of the line signahng device 9. In Fig. 2 there is shown a telephone line C which is provided with the usual line relay 15 and cutoff relay l6. ThlS line is also provided with a third relay 17 which cooperates with the line and cutofi relays to prevent the false operation of the line signaling device 19.

With this brief description of the drawlngs in mind, it is thought that the invent on may be best understood from a descrip tlon of the operation of the circuits disclosed.

Subscriber A in initiating a call removes the receiver from the switchhook, thereby causing the operation of line relay 5 over a clrcuit from battery through the winding of line relay 5, left-hand normal contact of cutofi relay 6 cut over one side of the line, through the switchhook contact, back over the other side of the line, and righthand normal contact of cutoff relay 6 to ground. Line relay 5, in operating, causes the line lamp 9 to be lighted. The operator upon observing the lighted condition of the line lamp 9 inserts plug 20 of cord circuits B into jack 21, thereby causing the operation of the cutoff relay 6 over a circuit from battery through supervisory lamp 22, resistance 23, sleeve contacts of the plug 20 and the jack 21, normal contact of relay 8, and the Winding of cutoff relay 6 to ground. Cutoff relay 6, in operating, disconnects the line relay from the line, which thereupon releases, extinguishing the line lamp 9. The closure of the alternate contact of the cutoff relay 6 causes the operation of relay 7 over a circuit from battery through the righthand winding thereof and the alternate contact of cutoff relay 6 to ground. While there is a tendency for the supervisory lamp 22 to light over the circuit previously traced, supervisory relay 24 operates so soon after the closure of the circuit through the lamp, that a shunt circuit including resistance 25 is established for the lamp before it lights.

If, while the receiver is off the switchhook, the central office operator withdraws the plug 20 from the jack 21, cutoff relay 6 is immediately released and line relay 5 operates. Relay 7 is of the slow-releasing type so that line relay 5 operates before the alternate contactof relay 7 is opened' relay 7 is locked up, line lamp 9 cannot be lighted While the receiver remains ofl' the switchhook. If the receiver is restored to the switchhook line relay 5 releases, opening the locking circuit of relay 7 and the ener gizing circuit of relay 8, which thereupon release their armatures, restoring the apparatus associated with the line to normal condition. If the operator should insert. the plug 20 into line jack 21before the receiver is restored to its switchhook, relays 7 and 8 immediately release. This is brought about by the establishment of a circuit from battery through lamp 22, resistance 23, sleeve contacts of the plug 20 and the jack 21, alternate contact of relay 8, left-hand winding of relay 7, winding of relay 8, alternate contactof relay 7 and contact of line relay 5 toground. The two windings of the relay 7 are now connected in parallelopposing, so that the energizing effects of the two windings are neutralized. Relay 7 thereupon releases its armature, opening the energizing circuit of relay 8. Relay 8 re leases, reestablishing the energizing circuit of-cutoff relay 6. Cutofi relay 6 thereupon operates, disconnecting the line relay 5 from the line.

Subscriber C (see Fig. 2) in initiating a call removes the receiver from the switchhook, thereby causing the operation of line relay 15. Line lamp 19 is thereupon lighted over a circuit from battery through the lamp 19,7left-hand normal contact of relay 17 and the contact of line relay 15' to ground. The operator upon observing the lighted condi tion of the line lamp l9 inserts plug 20 of the cord circuit B into jack 31, therebycausing the operation of cutofl relay 16 over a circuit from battery through the lamp 22, resistance 23, sleeve contacts of the plug 20 and jack 31, right-handnormal contactof relay 17 and the winding of cutoff relay 16toground, Relay 16, in operating, disconnects theline relay 15 from the line, which thereupon releases its armature, extinguishingthe line lamp 19. Relay 16, in operating, also causes the energization, of relay 17 over a circuit from battery through the two windings of relay17 (which are now connected in series-aiding) and contact 32 of cutoff relay 16 to ground. Relay 17 in operating, connects cutoff relay 16 in a circuit which includes the right-hand alternate Contact of relay 17 and alternate contact 33 off cutoff relay 16. If the operatornow withdraws the plug 20 from the jack 31 while the receiver is off the switchhook, cutoff relay 16immediately releases its arma- 'tures, whereupon line relay 15' operates;

Relay 17=is ofthe'slow-releasing type, so that line relay 15 closes its contact before relay 17 releases its armatures. Therefore a holding circuit for relay 17 is established from battery through the left-hand winding of relay 17, left-hand alternate contact thereofand the contact of line relay 15 'to ground. The circuit'herei-nbefore traced, which included the two windings of relay 17 connected in series-aiding, was interrupted at contact, 32-01 cutoff relay 16 upon the release thereof. Relay 17 being maintained energized,- prevents the lighting of line lamp 19. If the subscriber restores the receiver to the switchhook the release of line, relay, 15 causes all apparatus to be restored to nor mal position. However, if the'operator .inserts a plug into the jack 31 before the receiver is restored to the switchhook, relay 17 immediately releasesfits armatures, due tothe establishment of a circuit from battery through the supervisory lamp andthe sleeve resistance of the cord circuit,-sleevef contacts of the plug and the engaged. jack,

31, right-handalternate cont-act of relay 17, contact 34 of cutoff relay 16, right-hand winding of relay 17 left-hand alternate-contact thereof and the contact of line relay a telephone line, a line relay therefor, a line signal, a slow release relay coiiperatrng w th the line relay to control the line slgnal, a

cutoff relay controlling the line relay, a link circuit for extending the telephone'line, an energizing circuit for the slow release relay established upon the connection of the link circuit with the telephone line, a looking circuit for, the slow release rela'yjcom pleted upon the disconnection'of' the link circuit from the telephone line to prevent the operation of the line signal while the line is closed, anda deenergizing circuit forfthe" slow release relay established upon the sub sequent connection of the link circuit with' the telephone line.

2. In a telephone system, in combination,

line relay 15 a telephone line, a line relay therefor, a line signal controlled by the line relay, a link circuit for extending the telephone line, a cutofl relay operating upon the connection of the link circuit with the telephone line to remove the line relay from the control of the telephone line, and a slow release relay controlling the restoration of the line relay to the control of the telephone line when the link circuit is disconnected therefrom and the removal of such control therefrom upon the subsequent connection of the link circuit with the telephone line.

3. In a telephone system, in combination, a telephone line, a line relay therefor, a line signal, a slow release relay cooperating with the line relay to control the line signal, a cutoff relay controlling the line relay, a link circuit for extending the telephone line, an operating circuit for the cutoff relay established upon the connection of the link circuit with the telephone line, an energizing circuit for the slow release relay established upon the operation of the cutofi' relay, a circuit established upon the disconnection of the link circuit from the telephone line for maintaining the slow release relay energized and the operating circuit of the cutoff relay open, and a circuit including a winding of the slow release relay established upon the subsequent connection of the link circuit with the telephone line for causing the closure of the operating circuit of the cutofi relay.

4. In a telephone system, in combination, a telephone line, a line relay therefor, a line signal, a slow release relay having two windings and cooperating with the line relay to control the line signal, a cutofi' relay controlling the line relay, a link circuit for extending the telephone line, an operating circuit for the cutofi relay established upon the connection of the link circuit with the telephone line, an energizing circuit for the slow release relay established by the operation of the cutoff relay and including one of its windings, a circuit established upon the disconnection of the link circuit from the telephone line and including the one winding thereby to maintain the slow release relay energized and the operating circuit of cutoff relay open, and a second circuit including the second winding of the slow release relay established upon the subsequent connection of a link circuit with a telephoneline for rendering the slow release relay diflerential thereby to release the slow release relay and close the operating circuit of the cutoff relay.

5. In a telephone system, in combination, a telephone line, a line relay therefor, a line signal, a slow release relay cooperating with the line relay to control the line signal, a cutofi relay controlling the line relay, a link circuit for extending the telephone line, an operating circuit for the cutofi relay established upon the connection of the link circuit with the telephone line, an energizing circuit for the slow release relay established upon the operation of the cutoff relay, a locking circuit for the slow release relay established upon the disconnection of the link circuit from the telephone line to prevent the operation of the line signal while the line is closed, a fourth relay energized upon the establishment of the locking circuit to open the operating circuit of the cutoff relay, a deenergizing circuit for the slow release relay established upon the subsequent connection of the link circuit with the telephone line for causing the release of the fourth relay and the closure of the operating circuit of the cutoff relay.

In Witness whereof I hereunto subscribe my name this 25th day of March, A. D. 1918.

HORACE W. ULRICH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

